Transmission electron microscopy study of (103)-oriented epitaxial SrBi2Nb2O9 films grown on (111) SrTiO3 and (111) SrRuO3/(111) SrTiO3

Portions of the same epitaxial (103)-oriented SrBi2Nb2O9 film grown on (111 ) SrTiO3 for which we recently reported the highest remanent polarization ( P-r) ever achieved in SrBi2Nb2O9 (or SrBi2Ta2O9) films, i.e., P-r = 15.7 mu C/cm(2), have been characterized microstructurally by plan-view and cross-s ectional transmission electron microscopy (TEM) along three orthogonal view ing directions. SrBi2Nb2O9 grows with its c axis tilted 57 degrees from the substrate surface normal in a three-fold twin structure about the substrat e [111], with the growth twins' c axes nominally aligned with the three [10 0] SrTiO3 directions. (103) SrBi2Nb2O9 films with and without an underlying epitaxial SrRuO3 bottom electrode have been studied. Dark-field TEM imagin g over a 12 mum(2) area shows no evidence of second phases (crystalline or amorphous). A high density of out-of-phase boundaries exists in the films.